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Arun C Murthy commented on MAPREDUCE-1700:
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Tom, I don't understand specific advantages of OSGI or Felix, so please pardon some of my
questions.
However, with MR being an application in YARN (see MAPREDUCE-4421) we can just add user jars
in front of the classpath for the tasks (we already allow it). This isn't the same Map/Reduce
child inherits the TT classpath problem in MR1 (actually even in MR1 you can put child jars
ahead in the classpath for a long while now). Given this, do we need to bring in OSGI or Felix,
what do else do they provide? Thanks.
> User supplied dependencies may conflict with MapReduce system JARs
> ------------------------------------------------------------------
>
> Key: MAPREDUCE-1700
> URL: https://issues.apache.org/jira/browse/MAPREDUCE-1700
> Project: Hadoop Map/Reduce
> Issue Type: Bug
> Components: task
> Reporter: Tom White
> Assignee: Tom White
> Attachments: MAPREDUCE-1700.patch, MAPREDUCE-1700.patch
>
>
> If user code has a dependency on a version of a JAR that is different to the one that
happens to be used by Hadoop, then it may not work correctly. This happened with user code
using a different version of Avro, as reported [here|https://issues.apache.org/jira/browse/AVRO-493?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=12852081#action_12852081].
> The problem is analogous to the one that application servers have with WAR loading. Using
a specialized classloader in the Child JVM is probably the way to solve this.
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